JPH11133907A - Crt display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correspond to a personal computer using a different R, G, B output signal voltage so as to display a vivid image by lowering the gain of a gain variable type preamplifier by a value corresponding to the excessive quantity. SOLUTION: When processing by a CRT display device 1 is started, an amplitude peak value is detected on the basis of the R, G, B voltage values obtained by a detecting circuit 6A, and compared with a preset reference value. In the case where the detected amplitude value exceeds the reference value, a difference between the amplitude peak value and the reference value is obtained per each R, G, B signal. The signal for lowering the gain of a gain variable type preamplifier 3 by a value corresponding to the excessive quantity of the amplitude peak value is output to a D/A converter 7b. Gain of the preamplifier 3 is lowered, and the amplitude peak value to be detected is lowered to the reference value or less. With this structure, lowering of visibility of a CRT 5 is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT display device suitable as a color monitor of a personal computer and the like.
In particular, a CRT display capable of always displaying clear images by automatically responding to personal computers with different R, G, B output signal voltages due to differences in design specifications between manufacturers and poor adjustment of video boards, etc. Related to the device.

[0002]

2. Description of the Related Art As is well known, a CRT display device suitable as a color monitor or the like of a personal computer receives R, G and B signals which are video signals output from a built-in video board or the like of the personal computer to be used for color. It is configured to display an image.

By the way, R, output from a personal computer,
It can be seen that the amplitudes of the G and B signal voltages are slightly different due to differences in design specifications between manufacturers, poor adjustment of the video board, and the like.

[0004]

However, the CRT
The R, G, B input signal voltage specifications on the display device side are as follows:
Generally, it is fixed for each manufacturer. For example, when the input signal voltage is 0.7 Vp-p, the cathode voltage of the CRT becomes 50 Vp-p, and the setting is made so that an optimal viewing environment is obtained in this state. Therefore, if the R, G, B signal voltage output from the personal computer does not match the R, G, B input signal voltage specification of the CRT display device,
When the R, G, and B signals exceeding the input signal voltage specification arrive from the personal computer side, there is a problem that the focus is deteriorated and the visibility is significantly reduced.

The present invention has been made in view of the above-mentioned problems, and has as its object the purpose of making R, G, R, G, and R due to differences in design specifications between manufacturers and poor adjustment of video boards. It is an object of the present invention to provide a CRT display device which can automatically display a clear image by automatically responding to personal computers having different B output signal voltages.

[0006]

According to a first aspect of the present invention, there is provided an R, G, B input terminal to which R, G, B signals supplied from the outside are respectively inputted, and the R, G, and B input terminals. , B
Variable gain preamplifier for amplifying the R, G, B signals input to the input terminal and initial setting to a predetermined gain, and an output for power amplifying the R, G, B signals output from the variable gain preamplifier An amplifier and a CRT driven by being supplied with R, G, B signals output from the output amplifier
And amplitude peak value detecting means for respectively detecting amplitude peak values of R, G, B signals at predetermined points in a signal path from the R, G, B input terminals to the CRT, and an initial setting state of the variable gain preamplifier. A reference value excess determining means for determining whether or not the amplitude peak values of the R, G, B signals detected by the amplitude peak value detecting means exceed a reference value; CRT display comprising: gain control means for lowering the gain of the variable gain preamplifier by a value corresponding to the amplitude peak value excess when it is determined that the value exceeds the reference value. In the device.

In the invention according to claim 2 of the present application, the amplitude peak value detecting means is arranged so that, at a predetermined point set between an output side of the preamplifier and an input side of the output amplifier, R, G, The CRT display device according to claim 1, wherein an amplitude peak value of the B signal is detected.

In the invention according to claim 3 of the present application, the amplitude peak value detecting means is arranged such that R, G, and R are detected at predetermined points set between the output side of the output amplifier and the input side of the CRT. The CRT display device according to claim 1, wherein an amplitude peak value of the B signal is detected.

According to a fourth aspect of the present invention, the reference value excess judging means sets the amplitude peak value to a reference value if any one of the R, G, and B signals exceeds the reference value. The CRT display device according to claim 1, wherein it is determined that the value is exceeded.

According to a fifth aspect of the present invention, when the two or more of the R, G, and B signals exceed a reference value, the gain control means determines the maximum excess of the R, G, and B signals as the amplitude. The CRT display device according to claim 1, wherein the peak value is exceeded.

According to these inventions, a personal computer having different R, G, and B output signal voltages due to a difference in design specifications between manufacturers or an improper adjustment of a video board, etc., is automatically adapted to always correspond. CRT capable of displaying clear images
A display device can be provided.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a hardware configuration of a CRT display device according to a first embodiment of the present invention. As shown in FIG. 1, the CRT display device 1 has R, G, and B input terminals 2a, 2b, and 2c to which R, G, and B signals supplied from the outside are input, respectively.
A variable gain preamplifier 3 for amplifying R, G, B signals input to the R, G, B input terminals 2a, 2b, 2c with the same gain and initial setting to a predetermined gain; An output amplifier 4 for power-amplifying the R, G, B signals output from the preamplifier 3, and a CRT 5 to which the R, G, B signals output from the output amplifier 4 are supplied and driven.
And

In addition to the above configuration, the CRT display device 1 has the R, G, B input terminals 2a, 2b,
Amplitude peak value detection means for detecting the amplitude peak values of the R, G, and B signals at predetermined points in a signal path from 2c to CRT5; and, in an initial setting state of the variable gain preamplifier, the amplitude peak value detection means. Exceeding reference value judging means for judging whether or not the detected amplitude peak values of the R, G, B signals exceed the reference value, and determining that the amplitude peak value exceeds the reference value by the reference value excess judging means. And gain control means for lowering the gain of the variable gain preamplifier by a value corresponding to the excess of the amplitude peak value when the determination is made. In the first embodiment, the "amplitude peak value detecting means", the "reference value excess determining means", and the "gain control means" are realized as follows by a detecting circuit 6A and a control circuit 7, which will be described later. Have been.

The detection circuit 6A has a function of detecting the amplitude peak values of the R, G, and B signals at a predetermined point set between the output side of the preamplifier 3 and the input side of the output amplifier 4. For example, a resistance element for detecting the voltage of each of the R, G, and B systems and an A for converting the R, G, and B voltages detected by the resistance elements into a digital value.
/ D converter and the like.

The control circuit 7 generates a gain control signal for controlling the gain of the preamplifier 3 by executing a predetermined operation (described later) based on the detected voltage value output from the detection circuit 6A. And a D / A converter 7b that A / D converts a gain control signal output from the microcomputer 7a and supplies the signal to the preamplifier 3. .

Next, the content of the operation executed by the microcomputer 7a will be described in detail with reference to the flowchart of FIG. This flowchart shows the configuration of a control program for realizing “amplitude peak value detecting means”, “exceeding reference value determining means”, and “gain controlling means” according to the present invention by a computer. The program is stored in the ROM in the microcomputer 7a.

In FIG. 1, for example, when the process is started by turning on the power of the CRT display device 1 or the like (steps 311, 321, 331), based on the R, G, B voltage values obtained from the detection circuit 6 A, The peak amplitude value (this corresponds to the cathode amplitude of the CRT 5) is detected for each of the R, G, and B signals (steps 312, 322, and 3).
32). The detection of the amplitude peak value can be executed, for example, by a process of obtaining the maximum value among the instantaneous amplitude values detected in one or more predetermined horizontal scanning line periods. FIG. 4A shows the detected amplitude peak value A only for the video R signal. The same applies to the amplitude peak values B and C in the other signal systems (G and B).

Next, the detected amplitude peak values A, B, and C of the R, G, and B signals are set to a predetermined reference value D.
(Steps 313, 323, 333). Here, the value of the reference value D is set corresponding to the maximum amplitude value (for example, 50 Vp-p) allowed for the cathode voltage of the CRT 5 from the viewpoint of providing an optimal viewing environment. That is, in these comparison processes, it is determined whether or not the amplitudes of the video R, G, and B signals transmitted from a personal computer or the like are within a specified value for the CRT display device. In FIG. 4B, R, G,
B shows the value of the reference value D common to each system.

As a result of the comparison, when it is determined that the detected amplitude peak values A, B, and C do not exceed the reference value D (steps 313NO, 323NO, and 333NO), the amplitude peak values fall within the specified values. As long as the value falls within the range, the above-described amplitude peak value detection processing is repeated (steps 312, 322, and 332).

On the other hand, as a result of the comparison, when it is determined that the detected amplitude values A, B, and C exceed the reference value D (YES in steps 313, 323, and 333Y).
ES), a process of obtaining a difference between the amplitude peak value and the reference value for each of the R, G, and B signals is executed according to the following equation (Equation 1) (steps 314, 324, and 334). As is clear from the figure, these deviation calculation processes (steps 314, 324,
334) is executed immediately when the amplitude peak values A, B, C exceed the reference value D in any of the R, G, B signals. This is because if any one of the R, G, and B signals exceeds the reference value D, the visibility may be reduced due to a focus shift. When only one of the R, G, and B signals exceeds the reference value, the amplitude peak value detection process is repeated for the other signal systems.

[0022]

X1 = Detection A-Reference D X2 = Detection B-Reference D X3 = Detection C-Reference D (Equation 1) In FIG. 4C, the deviation X1, the detection A, and the reference value D are shown.
Is shown. The same applies to the relationship between deviation 2 and detection B and reference D, and the relationship between deviation 3 and detection C and reference D in other systems.

Thereafter, the excess amplitude E is calculated to determine the gain control amount described later (step 34).
5). In this example, the process of calculating the excess amplitude E is performed by determining the largest one among the previously obtained deviations X1, X2, and X3 as the excess amplitude E. This is to ensure that the amplitude peak value does not exceed the reference value D in any of the R, G, and B signals as a result of the gain control processing described later.

After the excess amplitude E is determined in this way, subsequently, a gain control process (step 346) is executed to adjust the gain of the preamplifier 3 to keep the cathode voltage within a specified value. Is done. In this gain control processing, a signal for lowering the gain of the variable gain type preamplifier by a value corresponding to the amplitude peak value excess amount E is D / A
The process of outputting to converter 7b is performed. Then D /
The gain of the preamplifier is appropriately reduced in response to the output of the A converter 7b, and as a result, the detected amplitude peak values A,
Both the values of B and C fall below the reference value D, thereby avoiding a decrease in visibility on the CRT 5. FIG. 4D shows the content of the detection A after the gain reduction processing. As is clear from the figure, the detection A falls within the reference value D.

Next, a second embodiment of the CRT display device 1 according to the present invention is shown in FIG. In the figure, the same components as those of the first embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the second embodiment resides in that the detection position of the amplitude peak value is changed. That is, in the figure, the detection circuit 6B is provided with a predetermined point 9 set between the output side of the output amplifier 4 and the input side of the CRT 5.
In a, 9b, and 9c, the amplitude peak values of the R, G, and B signals are detected. For example, a resistance element for detecting a voltage of each of the R, G, and B systems and the resistance element detected by the resistance element are used. A / D for converting R, G, B voltages into digital values
It is composed of a converter and the like.

According to the second embodiment, although there is a drawback of handling a high voltage, since the cathode voltage of the CRT 5 can be directly detected, there is an advantage that control reliability is high.

[0028]

As is apparent from the above description, according to the present invention, it is possible to provide a personal computer having different R, G, B output signal voltages due to a difference in design specifications between manufacturers or an improper adjustment of a video board. Can automatically provide a CRT display device capable of always displaying clear images.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a CRT display device according to the present invention.
FIG. 2 is a block diagram illustrating a hardware configuration of the embodiment.

FIG. 2 shows a second embodiment of the CRT display device according to the present invention.
FIG. 2 is a block diagram illustrating a hardware configuration of the embodiment.

FIG. 3 is a flowchart illustrating a configuration of a control program executed by a microcomputer.

FIG. 4 is a waveform diagram conceptually showing a waveform corresponding to an amplitude peak value (A), a reference value (D), a deviation (X1), and a control result for a video R signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CRT display apparatus 2a, 2b, 2c Input terminal 3 Variable gain type preamplifier 4 Output amplifier 5 CRT 6A, 6B detection circuit 7 Control circuit 8a, 8b, 8c Predetermined point for signal detection 9a, 9b, 9c For signal detection Predetermined point

Claims (5)

[Claims] An R, G, B input terminal to which R, G, B signals supplied from the outside are respectively inputted, and an R, G, B signal inputted to the R, G, B input terminal are the same. A variable gain preamplifier that amplifies the gain with a predetermined gain and is initially set to a predetermined gain; an output amplifier that power amplifies R, G, and B signals output from the variable gain preamplifier; and an output that is output from the output amplifier A CRT driven by supplying R, G, and B signals; and amplitude peaks for detecting amplitude peak values of the R, G, and B signals at predetermined points in a signal path from the R, G, and B input terminals to the CRT. Value detection means, and a reference value for determining whether or not the amplitude peak values of the R, G, and B signals detected by the amplitude peak value detection means exceed a reference value in an initial setting state of the variable gain preamplifier. Super Determining means for controlling the gain of the variable gain preamplifier by a value corresponding to the amplitude peak value excess when the amplitude peak value exceeds the reference value by the reference value excess determining means; CRT display device comprising: 2. The apparatus according to claim 1, wherein said amplitude peak value detecting means detects an amplitude peak value of an R, G, B signal at a predetermined point set between an output side of said preamplifier and an input side of said output amplifier. The CR according to claim 1, wherein
T display device. 3. The amplitude peak value detecting means detects an amplitude peak value of an R, G, B signal at a predetermined point set between an output side of the output amplifier and an input side of the CRT. The CRT display device according to claim 1, wherein: 4. The method according to claim 1, wherein the reference value excess determination means comprises R, G, B
The CRT display device according to claim 1, wherein if any one of the signals exceeds the reference value, it is determined that the amplitude peak value exceeds the reference value. 5. The gain control means according to claim 2, wherein when two or more of the R, G, B signals exceed a reference value, a maximum excess of the R, G, B signals is taken as the excess amplitude peak value. The CRT display device according to claim 1.